A prominent New York financier and art collector, Ezra Merkin, has been charged with a $2.4bn fraud for collecting money from clients under false pretences and secretly handing it to the jailed fund manager Bernard Madoff.

New York's attorney general, Andrew Cuomo, has accused Merkin of acting as a middleman for Madoff and using the proceeds to fill his apartment with $91m worth of art. Merkin has one of the world's largest collections of Mark Rothko paintings.

The charges came as French authorities seized a $7m yacht, Bull, moored near Madoff's Mediterranean villa in Cape d'Antibes. Bailiffs threw a chain around the propeller of the luxury 27-metre vessel in the latest in a series of international measures to impound Madoff's assets since the corrupt money manager pleaded guilty to 11 criminal counts last month.

According to yesterday's fraud charges, Merkin used social connections, including his position as president of an orthodox Manhattan synagogue, to generate customers for his management firm, Gabriel Capital Corporation. He pretended to manage three of Gabriel's funds while in reality entrusting their contents to Madoff. He is accused of false marketing and of ignoring "glaring red flags" that Madoff's returns were too good to be true, including two warnings from close colleagues.

"Merkin duped individual investors, non-profits and charities into believing he was responsibly managing their investments, when in actuality he was dumping then into history's largest Ponzi scheme," said Cuomo.